Use map to traverse accessibilityIds instead of the view tree

This is the first step to a few things including allowing for virtual nodes to have view backed descendants and siblings.
The main change in findViewByAccessibilityId SPI (its changed name and location, but it still is effectively the same thing) is that if something has a nodeProvider it will now still return view children.
I sifted through each use of the SPI and determined if they were an issue, and cleaned up any code in the process (Autofill cleanup is coming in a different CL).

Test: added a few simple unit tests, used talkback on system in a few places including virtual views, atest accessibility*, cts accessibility* (There were some failures here but they don't seem to be caused by this change, those are captured in these bugs b/120628276 b/120890822), CtsAutoFillServiceTestCases
Bug: 37714287

Change-Id: Id5807114fbb4c932eaea275dc2d94d0dbe25a8ae